The Parchments study is a mixed-methods investigation of the impact of receiving residency permits and of legal status changes, also known as regularisation, on the health and well-being of undocumented migrants in Geneva, Switzerland. In 2017, the study recruited adults aged 18 or older, not registered as asylum seekers, who were living in Geneva without a valid residency permit and had migrated to Switzerland from outside the European Union, with the intention of remaining in Geneva for at least 3 years. The 468 recruited participants were split into two groups: those eligible and undergoing, or who had recently undergone regularisation, and those who were ineligible or unwilling to apply for regularisation. Data was collected on participants four times: at baseline in 2017-2018, 2018-2019, 2020-2021 and lastly in 2021-2022.